1. Field of the Invention
The invention relates to an actuator that contains the following components; at least one magnet with a predetermined direction of magnetization, an electrically conductive coil with a longitudinal axis that is oriented in an essentially vertical position with respect to the direction of magnetization of the magnet and which can be operated by an electric current, with the coil being arranged in an offset position near the magnet in the direction of the magnetization of the magnet so that an air gap remains between the coil and the magnet and, viewed in a longitudinal direction of the coil, the magnet protrudes beyond the ends of the coil during a static state of the actuator, a ferromagnetic core of high permeability around which the coil is wound and which, viewed in the longitudinal direction of the coil, ends above and below the coil in collar-shaped projections made of a highly permeable ferromagnetic material.
Actuators of the type mentioned at the outset contain a spring-mass system able to oscillate that is initiated to oscillate when an alternating current is driven through the electrically conductive coil. The actuators are used for very diverse purposes, for instance, as linear motors in pumps, as oscillations generators, or as oscillation eliminators. In the latter case, an actuator of the type mentioned at the outset is connected in its mechanical effect to an oscillating component and oscillations are created in the actuator which are superimposed on the oscillations of the component. By a suitable choice of amplitude, frequency, and phase of the oscillations created by the actuator, the oscillations of the component are reduced or eliminated.
2. Discussion of Background Information
An actuator is known from DE 43 01 845 C1 that is used as the active oscillation eliminator for a machine component moving back and forth. The active oscillation eliminator contains a support plate, mounted to the machine component, on which an electrically conductive insertion coil is positioned stationarily. The insertion coil is concentrically enclosed radially inside and radially outside by a pot magnet. With the aid of spring elements, the pot magnet is connected in a springed manner to the support plate of the active oscillation eliminator and is guided by a guiding device arranged parallel to the axis of the insertion coil. When an alternating current is driven through the electrically conductive insertion coil, the pot magnet begins to oscillate. The oscillations of the pot magnet are superimposed onto the oscillations of the machine component such that a reduction or elimination of these oscillations results.
The active oscillation eliminator known from DE 43 01 845 C1 has a relatively simple design and an extensively linear operational behavior due to a consistent gap width of the air gap that is ensured by the guidance device of the pot magnet. However, it is discernible that the elimination force created by the pot magnet is relatively small in relation to its constructive size since, in the active oscillation eliminator, only relatively small periodic exciter forces can be created and the elimination force is proportional to the amplitude of the exciter force. In the oscillation eliminator, only an electrodynamic force, which develops from the electric current flowing through the insertion coil between the insertion coil and the pot magnet, acts as the exciter force. Since the elimination force created in an oscillation eliminator is also proportional to the size of the oscillating mass, this problem could be solved basically by an enlargement of the pot magnet. However, not all applications of the active oscillation eliminator provide a sufficiently large constructive space. Basically, the problem could also be solved by choosing the natural frequency of the oscillating mass-spring system to be the same as the one to be eliminated since, in this case, the amplitude of the inertial mass results in very high values at an accordingly small dampening. The smaller the dampening, however, the smaller also the bandwidth of the desired resonance superposition so that only in a small range of frequencies can large elimination forces be achieved. In summary, it can be seen that, with the aid of the active oscillation eliminators known from DE 43 01 845 C1 in the given construction volume of the oscillating system (i.e., in a predetermined mass of the pot magnet), only relatively smaller elimination forces can be created. Thus, only relatively small forces can be eliminated.
From the paper xe2x80x9cModeling and Analysis of a new Linear Actuatorxe2x80x9d by Renato Carlson, Nelson Sadowski, Alberto M. Beckert, Nelson J. Batistela (published at the Industry Application Conference 1995, 30th IAS Meeting IAS"" 95, Conference Record of the 1995 IEEE, Oct. 8-12 1995, Orlando, Fla.) a linear actuator of the above-mentioned type is known that is provided with two cuboid permanent magnets with an electrically conductive coil being provided, which is wound onto an iron core in the shape of a double T. The magnetization of the permanent magnets points to the electrically conductive coil that is positioned between the permanent magnets and the upper and lower surfaces of the permanent magnets, viewed in the longitudinal direction of the coil, are covered with iron. The two cuboid permanent magnets are then positioned between two cuboid iron blocks. Furthermore, the permanent magnets and the flux guiding pieces covering them at the upper and lower end, with the aid of coil springs mounted in a springed manner, the other components of the linear actuator, however, being mounted statically. When alternating current is guided through the electrically conductive coil, the permanent magnets mounted in a springed manner are excited into oscillations.
In the linear actuator according to the above-mentioned paper, large exterior exciter forces can be created since, in addition to the electrodynamic forces, magnetic reluctance forces additionally act between the parts of the actuator that are statically positioned and those positioned in a springed manner, with said forces all acting in the same direction and add to a great force summary. Thus, in the linear actuator according to the above-mentioned paper, relatively greater exciter forces can be created with relatively small constructive dimensions. However, it must be stated that the linear actuator known from the above-mentioned paper is provided with complicated design since it contains a multitude of parts that are separated from each other by air gaps.
The invention is based on developing an actuator having a simple design in which large excited forces can be created.
According to another embodiment, the invention provides for an actuator in which the magnet is embedded in a ferromagnetic jacket of high permeability that covers at least the surface of the magnet facing away from the coil and, viewed in the longitudinal direction of the coil, at least partially the upper and the lower surface of the magnet and in that either the embedded magnet is statically positioned and the coil, including the core, is positioned in a springed manner such that the coil, including the core, is able to perform oscillations in the longitudinal direction of the coil or the coil, including the core, is statically positioned and the embedded magnet is positioned in a springed manner such that it can perform oscillations in the longitudinal direction of the coil.
The components of the actuator that are positioned as being oscillating in a given case are made to oscillate when an alternating current flows through the coil of the actuator.
In addition to the uses mentioned at the outset, the actuator can be used to excite the masses in a motor vehicle positioned in a springed manner to oscillator for the purpose of superimposing these oscillations onto the distributing oscillations in the motor vehicle such that they are eliminated as much as possible. In this case, the force creating the oscillating mass of the actuator is used as the exciter force for another spring mass system. Since large exciter forces are created with the oscillating mass of the actuator according to the invention large masses can be excited to oscillate in the motor vehicle. For example, it is possible to position the battery of a motor vehicle in a springed manner and to excite it to oscillate with the aid of the actuator.
The advantages achieved with the invention can be seen in the simple design of the actuator since it contains only few components. In the simplest case, the actuator utilizes only two parts, namely of the coil wound around the core and the magnet, with one of the two components being positioned in a springed manner. In spite of this simple construction, large exciter forces can be created inside of the actuator since, in addition to the electrodynamic forces, magnetic reluctance forces acting parallel also act in the actuator when an alternating current flows through the electrically conductive coil (for details, see descriptive figures). Another advantage of the invention can be seen in the actuator having only one air gap between the magnet or the magnets and the electrically conductive coil. The number of air gaps is therefore reduced in reference to those known from the paper xe2x80x9cModeling an Analysis of a new Linear Actuator.xe2x80x9d Due to the lower number of air gaps, the actuator has only minor loss of magnetic flux so that the magnetic field created can be better utilized.
According to one embodiment of the invention, the actuator contains the following components: a ring-shaped magnet with a magnetization in a radial direction, an electrically conductive coil whose longitudinal axis is positioned in the radial direction of the magnetization and which is concentrically enclosed by the ring-shaped magnet such that an air gap remains between the magnet and the coil.
The advantage of this exemplary embodiment can be seen in the actuator having a rotationally symmetrical design in the longitudinal direction of the coil and only one ring-shaped air gap between the magnet and the coil so that the constructive volume of the actuator is used optimally. Additionally, all forces acting on the coil in the radial direction balance each other out and only a small minor loss of magnetic field occurs. Additionally, the actuator has a largely linear operational behavior in a corresponding positioning of the magnet or the coil wrapped around the core, since the width of the air gap between the ring magnet and the coil does not change. With regard to appropriately embodied bearings, reference is made to the descriptive figures.
According to another embodiment of the invention, the actuator contains the following components: two cuboid magnets largely separated from one another with faces whose surface normal points towards the positive or negative xe2x80x9cyxe2x80x9d direction, with the magnetization of the one magnet pointing towards the positive xe2x80x9cyxe2x80x9d direction and the magnetization of the other magnet pointing towards the negative xe2x80x9cyxe2x80x9d direction and with each magnet being embedded in a ferromagnetic jacket of high permeability which covers at least partially the facial surfaces of the magnets facing away from the coil and the surfaces of the magnet whose surface normals are pointed in the positive or negative xe2x80x9czxe2x80x9d direction and an electrically conductive coil whose longitudinal axis is oriented in the xe2x80x9czxe2x80x9d direction (or perpendicular to the y direction) and can be driven by an electric current with the coil being positioned between the magnets such that an air gap remains between the coil and each of the two magnets.
For describing this embodiment, a system of Cartesian coordinates was introduced in order to clarify the orientation of the separate components of the actuator. Here, it was assumed that the direction of the magnetization of the magnets are fixed in the xe2x80x9cyxe2x80x9d direction.
An advantage of this embodiment is to be seen in the magnets of the actuator being provided of a simple cuboid design and thus being easy to produce. Another advantage of the exemplary embodiment is to be seen in the actuator being provided with a design symmetrical to the xe2x80x9cx-zxe2x80x9d plane in which the longitudinal axis of the coil is positioned so that, in this exemplary embodiment, all forces acting in the xe2x80x9cyxe2x80x9d direction of the coil balance each other out as well when the two air gaps are provided with the same width between each of the magnets and the coil. Additionally, the actuator is provided with a largely linear operational behavior when the magnets or the coil wrapped around the core are positioned appropriately since the air gap between the magnet and the coil does not vary then. With regard to the positioning being embodied appropriately, reference is made to the descriptive figures here as well.
According to another embodiment, the coil of the actuator is short-circuited by a controllable electric consumer, in particular, by a controllable electric resistor. When a load is fixed to the components of the actuator positioned in a springed manner according to this improvement, the actuator acts as an active being with a variable dampening for this load. As soon a the load and thus the components of the actuator positioned in a springed manner are made to oscillate in the longitudinal direction of the coil by external influences, a voltage is induced in the coil due to the moving magnets and the magnetic field that permeates the coil, permanently changing its timing which leads to a flow of current in the coil. The electric energy is transformed into different forms of energy in the electric consumer through which the coil is short-circuited. Preferably, a controllable electric resistor is used as the electric consumer in which the electric energy is transformed into heat. The transformation of the oscillation energy of the load into different forms of energy, in particular heat, dampens the oscillations of the load. Here, the amount of the dampening can be adjusted by the controllable electric consumer. The dampening is the highest, for instance, when the electric resistance is increased. For instance, the motor of a motor vehicle can be considered as the load.
Preferably, the movable components of the actuator can be positioned via an elastomer bearing. Alternatively, other support springs, for instance, made of steel or another fiberglass-supported plastic, can be used.
The magnet or magnets can be positioned statically and the coil, including the core, can be positioned in a springed manner with the aid of coil springs whose longitudinal direction runs in the direction of the longitudinal axis of the coil. Preferably, the coil springs are positioned concentrically to the longitudinal axis of the coil.
The magnet or magnets are positioned statically and the coil, including the core, is positioned in a springed manner with the aid of leaf springs. The advantage of this improvement is to be seen in the leaf springs being flexible in one direction like coil springs, but, as opposed to coil springs they can absorb forces perpendicular to this direction without deforming to a large extent. The leaf springs are directed in the actuator such that the direction of the leaf springs, in which they can largely absorb the forces without deformation, span the air gap or air gaps (or such that their flexible direction runs in the direction of the longitudinal axis of the coil) so that it is ensured that the width of the air gap or air gaps remains largely constant during the operation of the actuator.
The invention also provides, viewed in the longitudinal direction of the coil, at least one leaf spring positioned above and below the core which is connected, on the one side, to the core in a mechanical connection and, on the other side, tightly clamped in a statical bearing. The longitudinal direction of the leaf springs is largely oriented perpendicularly to the longitudinal axis of the coil and can run in any direction, otherwise. However, the leaf springs are preferably oriented such that their longitudinal direction runs in the xe2x80x9cxxe2x80x9d direction. Such an arrangement of the leaf springs ensures that the width of the air gap between the coil and the magnets, between which the coil is positioned, remains constant during the entire oscillation process of the coil.
The invention further provides, viewed in the longitudinal direction of the coil, at least one leaf spring positioned above and below the coil in the central area, being in mechanical connection with the core, and clamped at both ends. The advantage of this improvement is to be seen in that no resulting torsion momentum is created during the operation of the actuator. Each leaf spring is clamped at its end in a movable bearing. In another exemplary embodiment each leaf spring is tightly clamped at its end and stretchable in its longitudinal direction.
The invention also contemplates, viewed in the longitudinal direction of the coil, one system of leaf springs provided each above and below the core, utilizing at least two leaf springs 26, 28 that are connected with each other in a mechanically effective connection, with at least one leaf spring 28 of each system of leaf springs being in mechanically effective connection with the core 10 and the other leaf spring 26 of each leaf spring system to the housing 24 of the actuator. Each of the leaf spring systems acts in the longitudinal direction of the coil like a coil spring; however, perpendicularly to this direction, it is largely stiff so that a constant width of the air gap is ensured during operation as well.
The advantage of this improvement is to be seen in the coil spring system having a simple design and creating no resulting torsion momentum during the operation of the actuator.
The invention also contemplates that both the leaf springs provided above and below the core are connected in an electrically conductive manner to, on the one side, the coil and, on the other side, the voltage source through which the current is created that is driven through the coil. The advantage of this improvement is in that the voltage source can be connected to the tightly clamped end of the leaf spring. In this case, the conductive connection of the voltage source to the leaf spring is not dynamically stressed even when the coil is made to oscillate. The conductive connection from the leaf spring to the coil is not dynamically stressed by the oscillations of the coil either, since the ends of the conductive connection do not move in relation to one another during an oscillation process.
At least one leaf spring is provided in an actuator above and below the core, viewed in the longitudinal direction of the coil, whose one end is in a mechanical connection with the first magnet and whose other end is in a mechanical connection with the second magnet and which are fixed in the central area.
The ferromagnetic core and the ferromagnetic jackets may utilize ferromagnetic sheet metal with high permeability that are separated from one another by insulating layers. The advantage of this improvement is to be seen inside of the ferromagnetic core and inside of the ferromagnetic jackets, no strong eddy currents can form when a magnetic flux fluctuating in its timing is guided through the ferromagnetic core and through the ferromagnetic jackets. The eddy currents are limited to the xe2x80x9cthicknessxe2x80x9d of the sheet metal, however, and therefore accordingly are weak. The resistance loss inside the ferromagnetic sheet metal and the heat of the ferromagnetic sheet metal developing as a result can therefore be disregarded. Another advantage of this improvement is to be seen in that the weakening of the magnetic field produced by the coil using the eddy currents can also be disregarded. The sheet metals maybe made from electric sheet metal or iron.
The magnet or magnets maybe embodied as permanent magnets. The advantage of this improvement is to be seen in that no current input is necessary for the magnet or magnets in order to create a magnetic field. At least one of the permanent magnets is embodiment as a side grounding magnet. The advantage of this improvement is to be seen in that side grounding magnets create a strong magnetic field per magnet volume, therefore, have a high energy density.
The invention also provides that the magnet or magnets are embodied as electromagnets. The advantages of this improvement is to be seen in that particularly strong magnetic fields can be created with the aid of electromagnets.
The core, around which the coil is wound, is embodied as a double T-shaped core whose longitudinal axis is positioned in the longitudinal direction of the coil. The advantage of this improvement is to be seen in that such a double-T-shaped core can be produced in a particularly simple manner. In particularly, it is easily possible to create, in particular, such a core from ferromagnetic sheet metals with a high permeability that are separated from one another by insulating layers.
The invention also provides for an actuator including a ferromagnetic jacket. At least one magnet is embedded in the jacket and includes a length, a first end, and a second end. Each of the first and second ends of the magnet include a surface which is at least partially covered by the jacket. A ferromagnetic core comprises a length, a first collar-like protrusion, and a second collar-like protrusion. An electrically conductive coil through which an electrical current may flow is mounted to the core. The coil comprises a length. The coil is arranged adjacent the magnet and separated from the magnet by a gap. The length of the magnet is greater than the length of the coil. At least one of the coil and the magnet is movably mounted. At least one of the coil and the magnet is statically mounted. One of the coil and the magnet is capable of vibrating while the other of the coil and the magnet remains static.
The gap may comprise an air gap. The at least one magnet may have a predetermined direction of magnetization and the coil may be arranged in an offset position in a direction of magnetization of the magnet. The first and second ends of the magnet may be adapted to protrude beyond the first and second ends of the coil. The ferromagnetic core may be of high permeability and the coil may be wound around the core and between the first and second collar-like protrusions, each collar-like protrusion being made of high-permeability ferromagnetic material. The ferromagnetic jacket may be of high permeability and cover entirely the surfaces of the first and second ends of the magnet. One of the magnet and the coil may be statically mounted while the other of the magnet and the coil may be mounted via at least one spring. The coil may comprise a longitudinal axis which is oriented essentially vertically to a direction of magnetization of the magnet. The magnet may be ring-shaped and magnetized in the radial direction. The electrically conductive coil may comprise a longitudinal axis which is arranged vertically to the radial direction of magnetization of the magnet, the coil being concentrically surrounded by the magnet in such a way that an air gap remains between the magnet and the coil.
The magnet may comprise two magnets. Each of the two magnets may comprise essentially cuboid magnets arranged at a distance from one another whose surface normals point in a positive and negative xe2x80x9cyxe2x80x9d direction, with a magnetization of one magnet pointing in the positive xe2x80x9cyxe2x80x9d direction and the magnetization of the other magnet pointing in the negative xe2x80x9cyxe2x80x9d direction. Each of the two magnets may be embedded in a ferromagnetic jacket of high permeability that covers, at least partially, a surface of each of the first and second end of the magnet, each surface of the magnet having a surface normal which points in a positive and/or negative xe2x80x9czxe2x80x9d direction. The electrically conductive coil may comprise a longitudinal axis arranged along the xe2x80x9czxe2x80x9d direction and wherein the coil is arranged between the two magnets in such a way that an air gap remains between the coil and each of the two magnets.
The actuator may further comprise one of a controllable resistor and a controllable source connected to the coil. The coil may be adapted to be short-circuited by a controllable electric consumer. The controllable electric consumer may comprise a controllable electric resistor. The magnet may be statically mounted and the coil may be spring mounted via at least one elastomer bearing. The jacket may be statically mounted and the core may be spring mounted via at least one elastomer bearing. The coil may be statically mounted and the magnet may be spring mounted via at least one elastomer bearing. The core may be statically mounted and the jacket may be spring mounted via at least one elastomer bearing. One of the magnet and the coil may be spring mounted via at least one of a spiral chain, a coil spring, and a leaf spring. One of the jacket and the core may be spring mounted via at least one of a spiral chain, a coil spring, and a leaf spring.
The actuator may further comprise at least one leaf spring arranged adjacent at least one of the first and second collar-like protrusions. The at least one leaf spring may have one end mechanically connected to the core and another end firmly fixed to a housing via a static bearing. The at least one leaf spring may have a middle portion which is mechanically connected to the core and at least one end connected to a housing. The at least one end may be connected to the housing via one of a static bearing, moving bearing, and a floating bearing. The at least one leaf spring may comprise at least two leaf spring arranged adjacent one another.
The actuator may further comprise at least one leaf spring system coupled to one of the coil and the magnet. The actuator may further comprise at least one leaf spring system coupled to one of the core and the jacket. The leaf spring system may comprise at least two leaf springs connected to one another and forming a mechanical working connection, and wherein the mechanical working connection connects the core to a housing. The leaf spring system may comprise at least two leaf springs connected to one another and forming a mechanical working connection, and the mechanical working connection may connect the jacket to a housing. At least one leaf spring may be connected in an electrically conductive manner to the coil and wherein the leaf spring is connected in an electrically conductive manner to a power source. The core and coil may be statically mounted and the jacket and magnet may be mounted with the aid of at least one leaf springs.
The actuator may further comprise at least one leaf spring coupled to a first collar-like protrusion and at least one leaf spring coupled to a second collar-like protrusion. The at least one magnet may comprise two magnets and may further comprise at least one leaf spring coupled to one magnet and at least one leaf spring coupled to the other magnet. The middle portion of at least one of the leaf springs may be coupled to at least one of the magnets. The ferromagnetic core and the ferromagnetic jacket may comprise a plurality of ferromagnetic sheets with high permeability, the sheets being separated from one another by insulating layers. The sheets may comprise electrical sheets. The magnet may comprise a permanent magnet. The permanent magnet may comprise a rare earth magnet. The magnet may comprise an electromagnet. The core may comprise a double T-shaped core.
The invention also provides for an actuator comprising a jacket. At least one magnet is attached to the jacket and comprises a length, a first end, and a second end. Each of the first and second ends of the magnet comprise a surface which is at least partially covered by the jacket. A core comprises a length. An electrically conductive coil through which an electrical current may flow is mounted to the core. The coil comprises a length and surrounds the core. The coil is arranged adjacent the magnet and is separated from the magnet by a gap. A distance between the surface of the first end of the magnet and the surface of the second end of the magnet may be greater than the length of the coil. At least one of the coil and the magnet is mounted to vibrate. At least one of the coil and the magnet is statically mounted. One of the coil and the magnet is capable of vibrating while the other of the coil and the magnet remains static.